Sex ratio adjustment in birds

Abstract In a number of bird species, the sex ratio of the broods is not random, instead it is re-lated to parental quality and environmental conditions. Several hypotheses have been proposed to explain this phenomenon, the so called sex ratio adjustment. According to these hypotheses, sex ratio adjust-ment is expected to evolve when the fitness benefit an offspring confers to the parents changes with ecological or social factors in a sex-specific way. Though many correlative and experimental studies support these hypotheses, there are still unresolved problems. In our paper, we provide details on the hypotheses related to sex ratio adjust-ment and explanations for the differences observed in sex ratio patterns between populations and years. Finally, we discuss the importance of sex ratio adjustment for species conservation